Neither the seat nor the copper washer appear to be damaged (which I managed to fish out from the injector well after I pulled the injector out). The kit contains three brass coated steel wire brushes for cleaning the carbon deposits from the inner side walls of the port and two silicone-nylon brushes for cleaning the base / injector seat area. These silicone-nylon brushes are specially designed to give a smooth and consistent finish to the aluminium surface, particularly important on the base sealing area, where ordinary steel wire brushes will tear and abrade the aluminium seat surface, meaning that the seat area may have to be recut. A set of six plugs (plus insertion rod) are provided to seal off the injector nozzle ports at the bottom of the main injector port, to stop any carbon or dirt entering the combustion chamber during the cleaning process, and a thin bore wire brush is provided to clean the injector nozzle port.